An Egyptian military vehicle on the road in Sinai. Isis has claimed responsibility for the attack on a security checkpoint in the area that killed at least 13.
Photograph: Asmaa Waguih/Reuters

At least 13 Egyptian policemen were killed in the Sinai peninsula when Islamic militants fired a mortar round at a security checkpoint in the city of Arish, security and medical sources said on Saturday.

Islamic State claimed responsibility on several websites for the attack and Egyptian state media later confirmed it.

Ambulances were subjected to heavy gunfire as they attempted to reach the wounded, sources said. Eyewitnesses reported hearing a massive explosion and said the city’s entrances and exits had been closed off by security forces.

Security sources said government forces later killed five of the militants who had carried out the attack.

Egypt is battling an insurgency that gained pace after its military overthrew President Mohamed Morsi of the Muslim Brotherhood, Egypt’s oldest Islamist movement, in mid-2013 following mass protests against his rule.

The insurgency, mounted by Isis’s Egyptian branch, Sinai Province, has killed hundreds of soldiers and police and started to attack western targets in the country.

President Abdel Fattah al-Sisi, the former military chief who led the overthrow of Morsi, describes Islamic militancy as an existential threat to Egypt, which is an ally of the United States. Isis controls large parts of Iraq and Syria and has a presence in Libya, which borders Egypt.